In developing the intake system for the one-rotor,
I got some surprise. When I got to the point of running both ports, side and
P-P, on one carb each, I tried to coordinate the cup(close-up butterfly) with
the carbs, there was no impact from the cup at idle or anywhere else up to
3500RPM. Starting the engine with the cup full open was
normal. Naturally, I removed the cup and the engine is just running
fine. Throttle response with the P-P carb alone is very smooth and solid. Idle
speed is now at 1500RPM with the mixture not optimized yet.
So much for the cup in my case only.
I what I observed here holds up, the combo port
idea may be dead making the one rotor a more simple and better
engine.
This also reminded me of the NSU Wankel Spider,
which did not have a cup and was running very fine.